Actuating mechanism for magnetos



Oct. 30 1923; 1,472,545

P. BROWN ACTUATING MECHANISM FOR MAGNETOS Filed Aug. 5/1921 INVENTOR ATTORNEY5.

Patented Oct. 30, 1923.

PHELPS BROWN, OF SPRINGFIELD, MASSACHUSETTS.

AUTUATING MECHANISM FOR MAGNETOS.

Application filed August 5, 1921.

To all whom it may concern:

Be it known that I, Pnnnrs BROWN, citizen of the United States, residing at Springfield, in the county of Hampden and State of Massachusetts, have invented new and useful Im rovements in Actuating Mechanism for Klagnetos, of which the following is a specification.

This invention relates to an improved ac tuating mechanism for magnetoes of the class wherein an armature is moved toward and away from a magnetic core to vary the flux flowing in a magnetic circuit. The movement of the armature in at least one direction is accomplished relatively rapidly to produce a sudden change in the magnetic circuit and the roduction of a spark.

One object o the invention is to provide in a device of this character, improved meaps for varying the time of actuation of the armature for the purpose of securing a retarded s ark from the magneto when the cam sha t is rotating at relatively slow speeds and an advanced spark when the cam shaft is rotating at a comparatively high speed.

Another object of the invention is to provide in a device of this character, an actuating means which is effective to permit rapid movement of the armature at normal engine speeds and with little noise of operation but which is not so efiective at very slow speeds, and a second actuatin means which is effective independently 0 engine speeds to permit rapid movement of the armature, but which is noise producing in operation, together with means for selectively operating the armature from either means.

A further object of the invention is to provide independent armature actuating mechanisms, and means for rendering either mechanism effective to actuate the armature.

Another object of-the invention is to provide in connection with an armature actuating means mounted in fixed relationwith the engine cam shaft, a device interposable between the armature and said means for varying the time at which said means is efi'ective to move the armature.

Other objects of the invention will ap-' Serial at. 490,013.

Fig. 2 is a fragmentary end elevation of the same; and

Fig. 3 is a fra mentary side elevational view similar to lfig. l and showing a different relative ositioning of the parts.

In the embo iment of the invention illustrated herewith, 10 designates a magneto, whichmay be of any desired construction, but, as shown, is of the general type disclosed in U. S. Letters Patent #1307343 granted to Phelps Brown on June 24, 1919.

n this type of magneto, there are two cores 11 which are. adapted to be connected by a I vertically movabl armature 12. Customarily, the armature 12 is moved relatively slowly toward the cores, but on the return movement is moved much more rapidly in order to produce a sudden change of flux 1n the magnetic circuit of which cores 12 form a part and it is this last named movement which results in the production of a spark from the magneto.

The driving mechanism for armature 12 generally comprises a cam which gradually raises the armature and then suddenly releases it for movement at much higher speed by a driving spring (not shown herein but fully dlSGlOSed in the above-named patent). The armature is actuated from the cam by a member 13 which in its lower forked portion 15 carries a roll 14 to engage the cam. In order to obtain a quick release of the cam follower 14 and permit a very ra id movement of the armature entirely in ependent of engine speeds, a cam, such as is shown at 20, has been employed, which cam has a radial let-off portion 24. A. cam of this type, although desirable in that it permits movement of the'armature entirely independent of engine s eed, is noise producing due to the free fal of the cam follower which it permits.

Experience has shown that at normal engine speeds a cam of the type shown at 19, having a more gradual let-off portion 21, will permit a sufiiciently rapid descent of armature 12 and will not produce the noise incident to cams like cam 20. At slow speeds, as on starting, the cam 19 will not permit a sufficiently quick release of the armature to result in a spark-of the desired intensity.

To reduce the noise of operation is important, and therefore a cam, such as cam without impairing the efliciency of the magneto at normal speeds. On starting, however, a cam, such as 20, which is more noisy in operation, can be used Without serious objection, for the noise will be of short duration and can be endured for the effectiveness of this type of cam at starting speeds. Therefore, I provide cams of both types and arrange to bring either one or the other into operation as desired.

' Cam" 19 is fixed to the cam shaft 17 and directly underlies the roll 14 as clearly shown in Fig. 2. On each side of cam 19 is a cam 20 and these two cams are fixed to shaft 17 and out of the path of roll 14. The cams 20 are, however, arranged to underlie the two spaced arms 15 of the forked lower end of member 13 and the lower ends of these arms are, by preference, nicely rounded concentrically with roll 14.

The normal position of parts is shown'in Fig. 3, wherein roll 14 bears on cam 19 and the rounded ends of arms 15 lie clear of the highest ints on cams 20. To make cams 20 effective to operate armature 12, means, as members 36, are interposed between the cams 20 and the rounded ends of arms 15, whereby the roll 14 is lifted free from cam 19 and the member 13 is lifted by enga ement of members 36 with the arms 15. v T lis condition is illustrated in Fig. 1.

The members 36 form the two s ced arms of a fork-like member 34 and the atter is flexibly connected to a rod 25 slidably mounted in a bracket 27 stationarily secured to some suitable means, as for example, the engine frame. The particular flexible connection shown between rod 25 and fork 34 consists of a closely wound coil spring 31, into one end of which the threaded end 30 of rod 25 is screwed, and the fork 34 is similarly held to the other end of spring 31 by a screw 32. Between the fork 34 and bracket 27 is a spring 37 which tends to move the fork toward the cams 19 and 21. The bracket 27 is so located vertically as to guide the fork between the cams and roll 14 and so located horizontally that the arms 36 of the fork will straddle roll '14 and thereby be so positioned as to ride on the peripheries of cams 20. The fork 34 is retractible manually and is held retracted by turning rod 25, when fully retracted, a quarter turn, which brings the bent portion 28 of rod 25 into engagement with an abutment 29 on bracket 27. The bentv portion 28 also by abutment with the hub portion of bracket 27, limits the degree of advancing movement of fork 34. In order to vary the outward position of fork 36, and thus vary the time at which it will be released by the radial surfaces 24 of cams 20, the bracket 27 is adjustably mounted, as by screws 41 which pass through longitudinal slots 40 in bracket 7 to permit. movement of the latter toward or away from cam 19.

In normal operation, the fork 34 is retracted, as shown in Fig. 3, and roll 14 rides on the periphery of cam 19. The cam shaft 17, turni in the direction of the arrow shown in ig. 1, gradually lifts roll 14 and raises armature 12 until it engages cores 11. As soon as roll 14 reaches the high point 22 of cam 19, the follower passes onto the incline 21 which connects the high oint 22 with the low point 23 of cam 19. his incline, while not nearly as steep as the radial surfaces 24 of cams 20, will at normal engine speeds permit the cam follower 14 to escend under the force of the armature driving springs with sufficient rapidity to cause an effective break in the magnetic circuit and without roducing the noise incident to a free fal of the follower 14. At relatively low speeds and on starting, the cam 20 does not permit the desired rap-id descent of the armature and, at such times, the fork 34 is released by disengaging the portion 28 from abutment 29 and turning it ninety degrees into the position illustrated in Fig. 1. Thereupon spring 37 advances the fork until its arms 36 straddle roll 14 and lie on cams-20. The member 15 is then lifted by cams 20 through the intermediary of the arms 36 of the fork, and the interposition of these arms hold roll 14 free from cam 19. With this condition, a rapid descent of armature 12 is permitted as soon as the tips of arms 36 reach the radial surfaces 24 of cams 20, and this descent is entirely independent of the speed of shaft 17. This drlving arrangement, although noisy in operation, is effective on-starting and since it is used only for short periods, the noise of operation is not a serious objection.

The use of an independent driving mechanism for starting an relatively slow engine s ds makes it possible to conveniently provide for the retarded spark desired from the magneto at such time, b setting the cams 20 so that their high points lie behind the high point 22 of cam 19 in the direction of revolution of shaft 17. This provides for a fixed degree of retardation of the spark.

The time of release of the armature 12, when actuated by earns 19, is not controlled by their relative location but is determined by the-position of fork 34 with relation to cams 19. Such position may be varied by in the annexed drawings has been described with considerable particularity in order that the construction and o eration of the same may be clear to those illed in the art, it is to be understood that the invention is not limited to the precise details of construction shown and described, nor any of them, except as the same are included in the followin claims.

hat I claim is- 1. In a magneto actuatingmechanism, a movable armtanre, a cam shaft, a cam carried by said shaft and adapted to actuate said armature, means interposable between said cam and armature for actuating the latter from the cam, and supporting means for the last-named means having a flexible connection therewith.

2. In a magneto, a movable armature, a drive shaft, two spaced cams thereon, a cam follower for the armature having a part normally directly engageable with one cam and an offset portion overlyin the other cam but held from engagement t erewith by said part, and means interposable between the second cam and said offset portion to actuate the armature therefrom and to hold said part out of engagement with the firstnamed cam.

a0 3.'In a magneto, a movable armature, a

drive shaft, a cam thereon, an actuatin member for the armature provided wit spaced arms, a cam follower mounted between and ex'tendin beyond said arms for engagement with sand cam, acam on each side of the first cam and underlying said arms, and a member having two spaced arms movable between said first named arms and last named cams to permit actuation of the armature from the latter and prevent its actuation by the first-named cams.

4. In a magneto, a movable armature, a drive shaft, a cam thereon, an actuatin member for the armature provided witfi spaced arms, a cam follower mounted between and extending beyond said arms for engagement with said cam, a cam on each side of the first cam and underlying said arms, and a member having two spaced arms movable between said first named arms and last named cams to permit actuation of the armature from the latter and prevent its actuation by the first-named cams, means to hold said member disengaged from the lastnamed cams, and means to move said memberon release of the last-named means toward said cams.

In testimony whereof I have aflixed my signature.

- PHELPS BROWN. 

